High tension cable



Aug. 1, 1933. K. A. HAANEN ET AL HIGH TENSION CABLE Original Filed July7, 1925 Patented Aug. 1, 1933 UNITED STATES HIGH TENSION CABLE KarlAugust Haanen,

Cologne-Mulheim, and

Hans Meurer, Cologne, Germany, assignors to Felten & GuilleaumeCarlswerk Actien-Gesellschaft, Cologne-Mulheim, Germany Originalapplication July 7, 1925, Serial No. 42,104, and in Germany December 27,1924, now Patent No. 1,808,407, dated June 2, 1931. Divided and thisapplication May 24, 1926.

Serial No. 111,396

1 Claim.

The insulation of` high-tension cables consists of cellulose andimpregnating compound. The cellulose is used in the form of unloaded andunsized paper. The cable papers used hitherto, whether smoothed on thecalendar or not, have a density of from 0.60 to 0.87, the term densitysignifying the quotient derived from the dry Weight per square metre ingrams and the calculated volume of a square metre of pulp in cubiccentimetres. This case is a division of the serial application No.42,104 nled on the 7th July, 1925, on which a patent has been issued on2nd June, 1931, under the No. 1,808,407.

It has now been found that, when using the same quantity of impregnatingcompound, the resistance `to puncture of high-tension cables increases,if by rolling or pressing the paper the volume proportion of celluloseto impregnating compound is raised to a certain favourable point. Whenthe pressure applied exceeds a certain amount, the cellulose bres are soWeakened that the resistance to tearing of the paper is inadmissablyreduced and it can no longer be Wrapped on.

The present invention relates to a new method of treating cable papers,which is to be carried out before the papers reach the wrapping machine,the method being based on the recognition of the fact that by it theresistance to puncture of the cable insulation is increased.

According to the invention the resistance to puncture of the cable paperis increased by the density of the paper being increased by rollingunder great pressure or by other pressure applying means, but n'o morethan the retention of the necessary tensile strength for wrapping theconductors will allow.

It has' been found that the pressures to be applied must be so greatthat the thickness of 0 the paper is reduced at least by 15% of itsorigl inal thickness. The pressure of the rollers can be raised to suchan extent that the thickness ofthe paper will be reduced to about 60%and more. respond to increases of density to from 0.90 to 1.30 and more.

.In papers treated in this manner it has been found that in spite of thegreater density of the paper the absorbent property is not only retainedbut is in most cases even increased.

The treatment by rolling under pressure or by other pressure applyingmeans may be carried out after the paper has been impregnated with asuitable impregnating medium, for instance paraffln, cable impregnatingcompounds Such rolling or pressing pressures cor-V or the like. Byrolling under pressure or by other pressure applying means'I the paperis given a smooth surface, which ensures the separate paper layers ofthe cable insulation lying particularly closely on one another. Thislatter point is also of great importance inobtaining high resistance topuncture.

The accompanying drawing illustrates, by way of example, a high tensioncable according to the present invention. y

d shows the conductors, b the insulation provided between theconductors, c is the paper insulation obtained in the manner abovereferred to, and d is the sheathing.

What we claim isz- An electric cable including a conducting core andinsulating-impregnated unloadedv and unsized paper covering said core,said paper having had its thickness reduced at least 15% from itsoriginal thickness by compression' thereof and having a density above0.9 grams per cubic centimetre in its unimpregnated state and thenecessary tensile strength for Wrapping it round the conducting core.

' KARL AUGUST HAANEN.

HANS MEURER.,

